Merger Driven Explosive Evolution of Distant Galaxies (Minor Mergers)

TL;DR

This paper models galaxy mergers using the Smoluchowski kinetic equation, showing that the explosive evolution of galaxy luminosity functions can be explained by merger dynamics, especially in the context of distant galaxies.

Contribution

It derives solutions for the galaxy mass function evolution considering low-mass mergers and explains the observed luminosity function slope change as a result of merger-driven explosive evolution.

Findings

Luminosity function slope evolution matches observed data in the Ultra Deep Hubble Field.

Explosive evolution depends on the uniformity of merger probability across galaxy masses.

The model links merger probability to the power-law behavior of galaxy luminosity functions.

Abstract

We derived solutions for the Smoluchowski kinetic equation for the mass function of galaxies, which describes mergers in differential approximation, where mergers with low-mass galaxies are the dominant factor. The evolution of the initial distribution is analyzed as well as the influence of the source represented by galaxies (halos) that separate from the global cosmological expansion. It is shown that the evolution of the slope of the power-law part of the luminosity function at a constant mass-to-luminosity ratio observed in the Ultra Deep Hubble Field can be described as a result of explosive evolution driven by galaxy mergers. In this case the exponent depends exclusively on the uniformity degree of merger probability as a function of mass.